LONDON, England (CNN) -- A helicopter fitted with thermal imaging equipment is being used on London's railways, doing a job in one day that previously took eight weeks when done manually.

Tube Lines, which operates three lines on the London Underground, used the helicopter in December to detect whether point heaters on overland parts of the train network were working effectively before the bitter winter frost arrived.

Heating pads allow points on the tracks, where the line moves so trains can change direction, to stay warm enough to function.

If they drop below five degrees Celsius, the points do not work and trains cannot be redirected.

Tube Lines spokesman Lee Jones told CNN that previously the job involved four to six people checking individual heaters using handheld infrared cameras, which took about eight weeks to complete.

"They would start at one end of the track and by the time they finished, there was a chance that pads at the beginning of the track may already be faulty."

He said that because the 200-odd heating pads on the tracks were not used during the summer months, it was crucial for Tube Lines to check in autumn whether they were working, before the first frost of the winter arrived.

If one pad on a crucial section of the track failed to work, it could stop the points from working, costing the company about £6,000 a minute in lost working time, Jones said.

"It means we can redirect our manual gang to get on with routine maintenance and eliminating future faults. It's a more effective use of resources," he said.

Previously, testing began in November but the helicopter allows Tube Lines to test the equipment as late as possible, ensuring the heaters are checked as close as possible to the first frost, allowing enough time to find faults and fix them.

During testing, all heating pads on the track are turned on, the helicopter -- fitted with a heat-seeking camera -- flies over 142km of tracks, checking locations where heaters are fitted.

It detects immediately whether a heater is functioning properly.

The helicopter, similar to those used by police forces during search and rescue operations, is not owned by Tube lines. The company hires it from a company called Helicentre, at a cost of between £15,000-20,000 a day.

When the points fail, it costs the company a lot more than the cost of hiring the helicopter for the day, Jones said.

He said the thermal imaging equipment onboard the helicopter can also detect faults in cables in the tracks, something difficult to detect manually.

And because the heat sensing equipment records the flight, staff are able to analyze whether there are any potentially dangerous trees, which could fall on the tracks during snow or heavy storms.

"Basically, it gives us a complete picture of the railways. It's so simple but it has so many benefits," Jones said.

This is the second year Tube Lines has used the helicopter to perform the task and Jones said it had reduced the number of points failures during the winter months by half last year.